Research by Arnon, R. and Sela, M. (1969), Proc. Nat. Acad. Sci. U.S.A. 62, 163-170, and Arnon, R. , Maron, E. , Sela, M. , and Afinsen, G. B. (1971), Proc. Nat. Acad. Sci. U.S.A. 68. 1450-1454 on the protein lysozyme using synthetic partial sequences has created the basis for the subsequent studies of a possible use of partial sequences from virus coat proteins or bacterial toxins which correspond to the antigenic regions of these pathogens to construct non-infectious substitute vaccines (Sela, M. (1974), Bull. Inst. Pasteur 72, 73-86; (4) Lerner, R. A. (1982) Nature (London) 199, 592; Sela, M. (1983) Biopolymers 415-424). Such synthetic vaccines were found to imitate the immunogenic potential of natural pathogens on the basis of the permanent immune response on the T and B cell plane and the full expression of the T.sub.h and B cells inducing determinants.
The general process of these experiments is currently based on the covalently linking via suitable reagents of synthetic peptide sequences of antigenic sequence domains of proteins to a carrier protein or to polymer compounds often with strongly immunogenic properties. The discovery of specific linking reagents has received increased attention Stevens, V. C. (1986), in Synthetic Peptides as Antigens, CIBA Foundation Symposium 119, Wiley, Chichester, pp. 200-225. In this connection, original research by the inventors has resulted in significant progress (Geiger, R., Moroder, L., and Wuensch, E. (1984) in Peptides 1984, (Ragnarsson, U., Ed.), Almquist and Wiksell Int., L Stockholm, pp. 451-456). Such peptide/protein conjugates have already been used for the immunization of experimental animals. The immune response can be further heightened by addition or incorporation of known immune adjuvants.
This research has led to the finding that (1) the dominant immune epitopes of viral coat proteins and bacterial toxins correspond to definite protein sequences in spatially fixed forms, and (2) the carriers of such epitope sequences not only contribute to a depot effect but also play a decisive role in the presentation of the epitope sequences for specific identification by the T.sub.h and B cells Review: Synthetic Peptides as Antigens. CIBA Foundation Symposium 119, Wiley, Chichester, 1986).
A synthetic vaccine against cholera and thermolabile E. coli toxin is described in DE-Al-34 30 894. The synthetic vaccine includes a product of the linking of a high molecular weight vehicle to a polypeptide corresponding to a part of the sequence of subunit B of the natural cholera toxin. The vehicle may be a suitable toxoid or a synthetic polymer of high molecular weight, such as an alanine-lysine polymer with a molecular weight of at least about 50,000.
The peptide chains of the immunoglobulins are known to be interconnected by way of a "hinge" region. The hinge region helps form the Y-shaped structure of the IgG molecule. The Y shape makes possible the flexibility of the IgG molecules required in antigen bonding.